Unitized battery package

ABSTRACT

An electrical energy source (5), comprises a power supply (14) located in a housing (16). The power supply has positive (22) and negative (24) terminals attached to it and to the exterior of the housing. Conductors (12) connect the power supply to the positive and negative terminals. The housing has one or more apertures (20) in it that correspond to the location of the power supply. A non-conductive film (36) having an adhesive portion (24) is adhesively bonded to both the power supply and the cover. The power supply can be one or more battery cells (10), and the housing typically consists of a top (18) and a bottom (20), each of which have openings that correspond to the battery cells. The cells are co-located with the openings so that the cylindrical wall (32) of the battery cell is tangent to the exterior (33) of the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.08/033,524, filed Mar. 19, 1993, entitled "Method of Bonding a BatteryPackage" by Venus D. Desai and Robert D. Kreisinger, filed concurrentlyherewith, and assigned to Motorola, Inc.

TECHNICAL FIELD

This invention relates in general to electrical energy sources and moreparticularly to a battery package.

BACKGROUND

Portable electronic devices, such as two-way radios, typically use anenergy source, for example a battery, to derive power necessary foroperation. A battery can comprise a single battery cell or a pluralityof battery cells arranged in various fashion, for example, in series,parallel, or a combination of series and parallel.

When an electronic device, such as a radio, is subjected to shock orvibration, for example when dropped, any movement of the battery cellscreated by the impact of the drop can cause a momentary loss of powerand result in unpredictable operation of the radio. During the drop, aphysical connection of one battery cell to another (or to the radio) canbecome momentarily broken or opened, causing a dysfunction or total lossof power to the device. An important point which must be considered inthe case of some portable communication devices, such as radios, is themass of the energy source is a large proportion of the total mass of thedevice. This creates problems in the design of a system to effectivelyretain the battery cells in a consistent position during operation inall possible orientations and modes.

Battery cells are typically cylindrically- or rectangularly-shaped andinclude positive and negative electrical contact surfaces at their ends.Consequently, the battery cell is generally located in a cylindrical orrectangular chamber formed within a battery housing. Typically, theinter-cell connections are provided by welding metal tabs between thecells.

In order to make an energy source having the highest energy density inthe smallest package, all of the interior volume of the housing shouldbe filled with the battery cells. This has led to the development ofprismatic or rectangular battery cells that efficiently fill cubic- orsquare-shaped housings. However, these cells are rather expensive andnot readily available on the mass consumer market. Typically,cylindrical battery cells are used and a significant portion of thehousing interior volume is wasted due to the attempt of placing roundcells in a square housing. However, this loss of energy density orefficiency is typically offset by the lower cost of the cylindricalcells versus the prismatic cells. When using cylindrical cells, specialtechniques must be used to maintain the cells in position during drop,requiring even more space in the housing. These positioning devicesreduce the overall volume utilization of the package, degrading theefficiency and increasing the package size.

In the prior art, the battery cells are typically held in place and keptfrom moving by dispensing a bead of hot-melt adhesive in the channel inbetween the neighboring cells. This method of dispensing hot-melt ismessy and slow and results in an inconsistent battery package which doesnot provide the high degree of reliability desired.

Clearly, what is needed is a method of providing a high-efficiency,high-energy density package at a low cost.

SUMMARY OF THE INVENTION

Briefly, according to the invention, there is provided an electricalenergy source, comprising a power supply located in a housing. The powersupply has positive and negative terminals attached to it and to theexterior of the housing. Conductors connect the power supply to thepositive and negative terminals. The housing cover has one or moreapertures in it that correspond to the location of the power supply. Anon-conductive film having an adhesive portion is adhesively bonded toboth the power supply and the cover.

In another embodiment of the invention, the power supply is one or morebattery cells, and the housing consists of a top and a bottom, each ofwhich have openings that correspond to the battery cells. The cells areco-located with the openings so that the cylindrical wall of the batterycell is tangent to the exterior of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded isometric view of a battery package in accordancewith the invention.

FIG. 2 is a cross-sectional view through section 2--2 of FIG. 1, priorto final assembly.

FIG. 3 is a cross-sectional view of a prior art battery package.

FIG. 4 is a cross-sectional view through section 2--2 of FIG. 1 afterassembly.

FIG. 5 is a cross-sectional view of another embodiment of the invention,through section 2--2 of FIG. 1.

FIG. 6 is a top plan view of a battery package in accordance with theinvention.

FIG. 7 is a front elevational view of a battery package in accordancewith the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

While the specification concludes with claims defining the features ofthe invention that are regarded as novel, it is believed that theinvention will be better understood from a consideration of thefollowing description in conjunction with the drawing figures, in whichlike reference numerals are carried forward.

Referring now to FIG. 1, an electrical energy source or battery package5 typically consists of a number of batteries or battery cells 10. Asused herein, the terms battery, battery cell and cell areinterchangeable and refer to the individual electrochemical unit,whereas the assembled group of batteries or battery cells is referred toas a battery package. The batteries 10 are interconnected by a conductormeans 12 which typically consists of a series of metal tabs welded sothat the positive terminal of one cell is interconnected with thenegative terminal of another cell. Each of the cells is sointerconnected to create a continuous electrical circuit, therebycreating a power supply means 14. Power supply means 14 may also haveother parts incorporated therein, such as resistors, thermistors,diodes, LEDs and other circuitry. Other means of energy storage, such aslarge capacitors, pseudocapacitors, or ultracapacitors may besubstituted for or added to the battery cells 10 in order to form apower supply means 14. The cover 34 and the adhesive layer 36 are shownin exaggerated thickness in order to provide the clarity and detailneeded to clearly illustrate the invention.

In order to contain the power supply means 14, a housing 16 is formedaround the power supply. The housing 16 typically consists of a topportion 18 and a bottom portion 20. Positive terminal 22 and negativeterminal 24 provide electrical contact to the exterior of the batterypackage 5. A first portion of each terminal is interconnected to theconductor means 12, and a second portion of each terminal is formed soas to reside on the exterior surface of the housing 16.

In order to provide a package having the minimum thickness and maximumutilization of the space on the interior of the package, a series ofapertures or openings 30 are provided in the top and/or bottom of thehousing. Depending upon the degree of efficiency desired, the apertures30 may be formed in both halves of the housing or simply in one half.

Referring now to FIG. 2, a cross-sectional view through section 2--2 ofFIG. 1, it can be seen that the battery cells 10 are situated in thehousing 16 such that the cylindrical-shaped battery is co-located withthe apertures 30 in the housing top 18 and bottom 20. This results inthe cylindrical walls of the battery cell 10 being substantially tangentto the exterior surfaces 33 of the housing. The openings 30 allow thehousing to be made substantially smaller than would normally be the caseby eliminating the need for a substantial wall thickness at the point oftangency between the battery and the housing. In the prior art, as shownin FIG. 3, the overall thickness of the housing is substantially thickerbecause of the need to provide a finite wall thickness at the tangentpoint between cell and housing.

In order to retain the battery cells 10 in position, to provide forenvironmental protection of the battery cells, and add further structureto the completed package, a cover 34 is placed over the top and/orbottom in order to cover the apertures 30, as shown in FIG. 2. The cover34 is affixed to the housing 16 and to the cells 10 using an adhesive36. The adhesive 36 may be a continuous film, a series of strips, or amesh in such form as desired by the designer; however, the adhesiveshould be a material that can be melted and/or cured, and should beconfigured in such a manner as to affix the cell and housing to theadhesive. Typical adhesives are hot-melt, a pressure-sensitive adhesivesuch as an acrylic material, or an epoxy. In the preferred embodiment ofthe invention, the adhesive 36 is a film of pressure-sensitive acrylicadhesive and the cover 34 is a polyester film such as MYLAR®.

FIG. 2 shows the assembled battery package 5 prior to the final assemblystep. Note that the batteries are located within the housing such thatthe individual battery cells are co-located with the apertures 30 in thetop and bottom, and that the cylinder walls 32 of the batteries aresubstantially tangent to an exterior surface 33 of the housing. Thecover 34 and the adhesive film 36 are in place and ready to be bonded toboth the housing and the cells. The assembly is then placed into anultrasonic welding apparatus such that ultrasonic horns 40 are incontact with the assembly. When the ultrasonic horns 40 are energized,heat is generated at the surfaces, causing the top 18 to be welded tothe bottom 20 and also causing the adhesive 36 to soften and deform.

As can be seen in FIG. 4, a first portion 42 of the adhesive becomesthinner and is bonded to the battery cell 10 and a second portion 44 ofthe adhesive is also deformed but is bonded to the housing top and/orbottom. The ability to locally deform the adhesive 36 by means ofultrasonic energy provides a significant enhancement in reducing theoverall size of the battery package. Note that the housing 16 is now aunitized package and that the joint or disjuncture between the top andbottom halves is no longer present because the two halves have beenultrasonically welded.

Referring now to FIG. 5, another embodiment of the invention, it can beseen that the adhesive 36 can also be placed on the interior of thehousing, forming another type of bond between the battery cells 10 andthe housing top and/or bottom halves 18 and 20. In this case, theadhesive is bonded to an interior surface 48 of the housing 16. As inthe case shown in FIG. 4, a unitized package is created because theadhesive material bonds to both the battery cells and the housing. Notealso that the first and second portions (42 and 44) of the adhesive aredeformed and are thinner sections after ultrasonic welding. It should beclear to the reader that ultrasonic energy provides a means of locallyheating and melting or deforming the adhesive at the desired spots,which could not be obtained in any other manner. For example,conventional heating with a hot platen would not properly melt theadhesive, and the assembly cannot be placed in an oven because thebattery cells cannot typically be subjected to temperatures in excess of65° C. for any substantial period of time. Use of ultrasonic welding andultrasonic energy allows materials of much higher melting points to beused, for example, melting points that are higher than the normalservice temperature of the batteries. It should also be noted that theultrasonic horn does not directly contact the parts being melted, forexample, the adhesive 36, but is indirect contact and the energy istransmitted through the cover 34.

Referring back to FIG. 1, it can be seen that the cover 34 can also takethe form a label 46. This can be done by simply imprinting on the coveror making the cover a thin film. This now provides a triplefunctionality to the cover, that is, the cover serves as a label, itserves as a cover to environmentally protect the battery package 5, andit also serves as a method to unitize and rigidize the battery cells 10within the package. A top view of one embodiment of the invention isshown in FIG. 6, where the label 46 is centrally located on the cover34, and the cover 34 is bonded to portions of the housing 16. In FIG. 7,a typical configuration of positive terminal 22 and negative terminal 24can be seen.

In summary, the battery package of the instant invention provides abattery package with minimum thickness at a low cost by usingconventional, cylindrical battery cells in order to form a unitizedbattery package. The use of thermoplastic adhesives that can be deformedby ultrasonic welding provides integrity and additional structure to thebattery package by bonding the cells to the housing in ahighly-efficient and repeatable manner. The battery package of theinstant invention provides a battery package of comparable size andenergy density to one fabricated using prismatic or rectangular cells atsubstantially reduced cost.

While the preferred embodiments of the invention have been illustratedand described, it will be clear that the invention is not so limited.Numerous modifications, changes, variations, substitutions andequivalents will occur to those skilled in the art without departingfrom the spirit and scope of the present invention as defined by theappended claims.

FIGURE REFERENCES

5--Battery package

10--Battery

12--conductor means

14--Power supply means

16--Housing

18--Top

20--Bottom

22--Positive terminal

24--Negative terminal

26--Terminal first portion

28--Terminal second portion

30--Aperture

32--Cylinder Wall

33--Exterior surface

34--Cover

36--Adhesive

40--Ultrasonic horn

42--First portion

44--Second portion

46--Label

48--Interior surface

What is claimed is:
 1. An electrical energy source, comprising:a housinghaving first and second parts; power supply means, disposed in thehousing, for providing electrical potential; positive and negativeterminals attached to the housing; conductor means for connecting thepower supply means to the positive and negative terminals; one or moreapertures in at least the first housing part, the aperturescorresponding to the location of the power supply means; and anon-conductive film having first and second opposing faces, the firstface having first and second adhesive portions, the first adhesiveportion bonded to the power supply means, and the second adhesiveportion bonded to the housing; and a cover bonded to a third adhesiveportion on the second face of the non-conductive film.
 2. The electricalenergy source as described in claim 1, further comprising a secondnon-conductive film having first and second adhesive portions and firstand second opposing faces, the first adhesive portion on the first facebonded to the power supply means, and the second adhesive portion bondedto the other part of the housing.
 3. The electrical energy source asdescribed in claim 2, further comprising a second cover bonded to athird adhesive portion on the second face of the second film.
 4. Abattery package, comprising:a housing comprising a first part attachedto a second part, each part having one or more apertures; positive andnegative terminals attached to the housing; a plurality of battery cellselectrically connected to each other and disposed in the housing, eachcell located to correspond to an aperture, such that a portion of eachcell is exposed in the aperture; conductor means for connecting theplurality of battery cells to the positive and negative terminals; afirst cover attached to an exterior portion of the first housing part, afirst portion of said cover adhesively bonded to said exposed portion ofthe battery cells and a second portion of said cover adhesively bondedto the first housing part; and a second cover attached to an exteriorportion of the second housing part, a first portion of said coveradhesively bonded to said exposed portion of the battery cells and asecond portion of said cover adhesively bonded to the second housingpart.
 5. A battery package, comprising:a plastic housing comprising atop attached to a bottom, each having one or more apertures; a pluralityof cylindrical-shaped batteries, each battery electrically connected toanother and disposed in the housing so that the cylinder wall of thebattery is co-located with an aperture in the top and the bottom and issubstantially tangent to an exterior surface of the housing; positiveand negative terminals situated in the housing, a first portion of eachterminal connected to the plurality of cylindrical-shaped batteries anda second portion providing an electrical connection on the exterior ofthe housing; a first cover attached to an exterior portion of the top bymeans of an adhesive material, a first portion of said cover adhesivelybonded with said material to said co-located battery cylinder walls anda second portion of said cover adhesively bonded with said material tothe top; and a second cover attached to an exterior portion of thebottom by means of an adhesive material, a first portion of said coveradhesively bonded to said co-located battery cylinder walls and a secondportion adhesively bonded to the bottom.
 6. The battery package asdescribed in claim 5, wherein the adhesive material is a hot melt glue.7. The battery package as described in claim 5, wherein the adhesivematerial is a pressure sensitive adhesive.
 8. The battery package asdescribed in claim 5, wherein the adhesive material is melted anddeformed by application of ultrasonic energy and mechanical pressure tothe cover.
 9. The battery package as described in claim 5, wherein theadhesive material is of non-uniform thickness.
 10. The battery packageas described in claim 5, wherein the first cover is a label.
 11. Thebattery package as described in claim 5, wherein the second cover is alabel.
 12. The battery package as described in claim 5, wherein thefirst and second covers are labels.
 13. The battery package as describedin claim 5, wherein the adhesive material is selected from the groupconsisting of unsupported adhesive film, single sided adhesive film, anddouble sided adhesive film.
 14. The battery package as described inclaim 5, wherein the adhesive material is a discontinuous adhesive film.15. A battery package, comprising:a housing comprising a first partattached to a second part, each part having one or more apertures;positive and negative terminals attached to the housing; a plurality ofbattery cells electrically connected to each other and disposed in thehousing, each cell located to correspond to an aperture, such that aportion of each cell is exposed in the aperture; conductor means forconnecting the plurality of battery cells to the positive and negativeterminals; a first cover attached to an exterior portion of the firsthousing part by an adhesive material, a first portion of said firstcover bonded to said exposed portion of the battery cells by locallydeforming the adhesive material with heat and pressure, and a secondportion of said cover bonded to said first housing part by locallydeforming the adhesive material with heat and pressure; and a secondcover attached to an exterior portion of the second housing part by anadhesive material, a first portion of said second cover bonded to saidexposed portion of the battery cells by locally deforming the adhesivematerial with heat and pressure, and a second portion of said secondcover adhesively bonded to the second housing part by locally deformingthe adhesive material with heat and pressure.